I don't like little flimsy phones. However, my current phone is at the upper limits of what I consider reasonable.

It's a ulefone 27T pro
Height: 182.8 mm
Width: 86.8 mm
Depth: 18.5 mm
Weight: 441 grams

I would say 500g is likely my hard limit, outside of special circumstances. As it stands, it doubles as a self defence weapon.